One needs to compare any proposed solution to the enclosure requirements.
The only thing that makes a Nema 1 evaluation different fro a Nema 3R evaluation is the "rain test"
An enclosure is exposed to a heavy rain, which is blown at a slight angle- probably similar to a 20mph wind. After the test, water is not allowed to have accumulated in the enclosure to where it contacts live parts.
Nema 3R, in other words, would be passed with an umbrella.
The classification has NO additional requirements for corrosion protection or weathering.
Hard as it may be to believe, in industrial cities a wood enclosure will outlast a painted/ plated/ sealed metal box many times over.
The condition of the materials at the time of the install is completely separate from the necessity to maintain the installation, or the requirement that they be suitable for the location. For example- a plastic box might concievably be made of a plastic that stands up fabulously to a corrosive environment- yet fails quickly in sunlight.
An electrician is expected to actually think....which is a scary concept in these days of "McManagement".
